Design Optimization of Machine-Tool Structures With Respect to Dynamic Characteristics

1983 ◽  
Vol 105 (1) ◽  
pp. 88-96 ◽  
Author(s):  
M. Yoshimura ◽  
T. Hamada ◽  
K. Yura ◽  
K. Hitomi

This paper proposes a design optimization method in which simplified structural models and standard mathematical programming methods are employed in order to optimize the dynamic characteristics of machine-tool structures in practical applications. This method is composed of three phases: (1) simplification, (2) optimization, and (3) realization. As design variables employed in this optimization are greatly reduced, machine-tool structures are optimized effectively in practice. With large design changes being conducted through this multiphase procedure, dynamic characteristics of machine tools can be greatly improved. This method is demonstrated on a structural model of a vertical lathe.

1987 ◽  
Vol 109 (1) ◽  
pp. 143-150 ◽  
Author(s):  
Masataka Yoshimura

This paper proposes a design optimization method of machine-tool dynamics based on clarification of competitive and cooperative relationships between characteristics. Clarification of competitive and cooperative relationships between characteristics results in division of design variables into three groups. The design variables of each group are determined in each of the three-phase design optimization procedures. The design decision problem in each procedure is far simpler and easier than that in usual design optimization methods, in which all design variables are determined at the same time. The competitive and cooperative relations between characteristics are first clarified. Next, algorithmic procedures of the design optimization method are constructed. The method is demonstrated on a structural model of a milling machine.


1984 ◽  
Vol 106 (4) ◽  
pp. 531-537 ◽  
Author(s):  
M. Yoshimura ◽  
Y. Takeuchi ◽  
K. Hitomi

This paper proposes a multiphase design optimization method using simplified structural models in order to minimize manufacturing cost of machine-tool structures under constraints of machining accuracy, machining productivity, and local deformations of structural members. The manufacturing cost is divided into three components—material cost, welding cost, and machining cost, each of which is minimized in the multiphase optimization process. The method is demonstrated on a structural model of a double-column machine tool.


Author(s):  
Masataka Yoshimura

Abstract This paper proposes a design optimization method consisting of the multiphase structural modeling of ideal, intermediate, and detailed models for machine structures. In this method, the ideal characteristics are first obtained for a specific ideal model. Then, the detailed designs are determined so that the characteristics in the detailed model are as close to the ideal characteristics as possible. For easily and surely obtaining the final detailed designs, an intermediate model is introduced between the ideal model and the detailed model. This method not only effectively generates optimum detailed designs of machine structures but also brings about an easy realization of the optimum characteristics in practical manufactured machine products. The proposed method is applied to a machine-tool structural model for demonstrating the effectiveness of the method.


Author(s):  
T Kobayashi ◽  
M Burdekin

Not only dynamic characteristics of machine tool structures but also those of workpiece fixtures are important in machine tools as they directly influence the dynamic rigidity at a cutting point. In this paper, the effects of damping characteristics of slideways on the dynamic characteristics of workpiece fixtures mounted on machine tool tables have been clarified both theoretically and experimentally. Furthermore, a design criterion of workpiece fixtures has been suggested.


2018 ◽  
Vol 37 (24) ◽  
pp. 1456-1467 ◽  
Author(s):  
S Murugan ◽  
PR Thyla

Machine tool structures find large-scale applications in various machining industries due to their necessity to design several kinds of machines. However, the vibration produced on machining is a significant problem which has to be overcome. To suppress the vibration, several researchers have attempted to enhance the machine tool structure’s dynamic characteristics in the recent past. The composite materials have risen up as a new kind of material for the manufacture of machine tool structures with producing lesser vibrations since the past few decades. To increase the production of precision products, machining should be done at high speeds without producing vibration. The dynamic characteristics such as natural frequency as well as damping of machine tool structures are very important parameters. Hence, the improvement of these parameters is nothing but the improvement of dynamic characteristics, as said earlier. Therefore, the present review elaborates various available reports on the improved dynamic characteristics of machine tools. The review focused mainly on mechanical and dynamic properties of alternate materials for machine tools with different composite materials. Furthermore, conflicting conditions of suitable alternate material for the preparation of machine tools are also focused in the present review. To the best of our knowledge, the review on the use of alternate materials for the manufacturing of machine tool structures has not been reported elsewhere and hence the present review will provide useful information for subsequent researchers to enhance the scope of research work in the area of manufacturing machine tool structures.


Author(s):  
Narasimha R. Nagaiah ◽  
Christopher D. Geiger

The design and development is a complex, repetitive, and more often difficult task, as design tasks comprising of restraining and conflicting relationships among design variables with more than one design objectives. Conventional methods for solving more than one objective optimization problems is to build one composite function by scalarizing the multiple objective functions into a single objective function with one solution. But, the disadvantages of conventional methods inspired scientists and engineers to look for different methods that result in more than one design solutions, also known as Pareto optimal solutions instead of one single solution. Furthermore, these methods not only involved in the optimization of more than one objectives concurrently but also optimize the objectives which are conflicting in nature, where optimizing one or more objective affects the outcome of other objectives negatively. This study demonstrates a nature-based and bio-inspired evolutionary simulation method that addresses the disadvantages of current methods in the application of design optimization. As an example, in this research, we chose to optimize the periodic segment of the cooling passage of an industrial gas turbine blade comprising of ribs (also known as turbulators) to enhance the cooling effectiveness. The outlined design optimization method provides a set of tradeoff designs to pick from depending on designer requirements.


2012 ◽  
Vol 457-458 ◽  
pp. 60-64 ◽  
Author(s):  
Hua Long Xie ◽  
Hui Min Guo ◽  
Qing Bao Wang ◽  
Yong Xian Liu

The optimization of spindle has important significance. The optimization method based on ANSYS is introduced and spindle mathematical mode of HTC3250µn NC machine tool is given. By scanning of design variables, the main optimized design variables are determined. The single objective and multi-objective optimizations are done. In the end, the main size comparison of spindle before and after optimization is given.


Author(s):  
Rami Mansour ◽  
Mårten Olsson

In reliability-based design optimization (RBDO), an optimal design which minimizes an objective function while satisfying a number of probabilistic constraints is found. As opposed to deterministic optimization, statistical uncertainties in design variables and design parameters have to be taken into account in the design process in order to achieve a reliable design. In the most widely used RBDO approaches, the First-Order Reliability Method (FORM) is used in the probability assessment. This involves locating the Most Probable Point (MPP) of failure, or the inverse MPP, either exactly or approximately. If exact methods are used, an optimization problem has to be solved, typically resulting in computationally expensive double loop or decoupled loop RBDO methods. On the other hand, locating the MPP approximately typically results in highly efficient single loop RBDO methods since the optimization problem is not necessary in the probability assessment. However, since all these methods are based on FORM, which in turn is based on a linearization of the deterministic constraints at the MPP, they may suffer inaccuracies associated with neglecting the nonlinearity of deterministic constraints. In a previous paper presented by the authors, the Response Surface Single Loop (RSSL) Reliability-based design optimization method was proposed. The RSSL-method takes into account the non-linearity of the deterministic constraints in the computation of the probability of failure and was therefore shown to have higher accuracy than existing RBDO methods. The RSSL-method was also shown to have high efficiency since it bypasses the concept of an MPP. In RSSL, the deterministic solution is first found by neglecting uncertainties in design variables and parameters. Thereafter quadratic response surface models are fitted to the deterministic constraints around the deterministic solution using a single set of design of experiments. The RBDO problem is thereafter solved in a single loop using a closed-form second order reliability method (SORM) which takes into account all elements of the Hessian of the quadratic constraints. In this paper, the RSSL method is used to solve the more challenging system RBDO problems where all constraints are replaced by one constraint on the system probability of failure. The probabilities of failure for the constraints are assumed independent of each other. In general, system reliability problems may be more challenging to solve since replacing all constraints by one constraint may strongly increase the non-linearity in the optimization problem. The extensively studied reliability-based design for vehicle crash-worthiness, where the provided deterministic constraints are general quadratic models describing the system in the whole region of interest, is used to demonstrate the capabilities of the RSSL method for problems with system reliability constraints.


Author(s):  
Taufik Sulaiman ◽  
Satoshi Sekimoto ◽  
Tomoaki Tatsukawa ◽  
Taku Nonomura ◽  
Akira Oyama ◽  
...  

The working parameters of the dielectric barrier discharge (DBD) plasma actuator were optimized to gain an understanding of the flow control mechanism. Experiments were conducted at a Reynolds number of 63,000 using a NACA 0015 airfoil which was fixed to the stall angle of 12 degrees. The two objective functions are: 1) power consumption (P) and 2) lift coefficient (Cl). The goal of the optimization is to decrease P while maximizing Cl. The design variables consist of input power parameters. The algorithm was run for 10 generations with a total population of 260 solutions. Although the number of generations and population size was limited due to experimental constraints, the algorithm was able to converge and the approximate Pareto-front was obtained. From the objective function space, we observe a relatively linear trend where Cl increases with P and after a certain threshold, the value of Cl seems to saturate. We discuss the results obtained in the objective space in addition to scatter plot matrix and color maps. This article, with its experiment-based approach, demonstrates the robustness of a Multi-Objective Design Optimization method and its feasibility for wind tunnel experiments.


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